Composer更新：请求的PHP扩展名ext-http丢失

I am creating a php website using the symfony framework and composer.

• Operating system: Windows 10
• PHP version: 7.3.2
• Symfony: 4.2.3 (env: dev, debug: true)
• Composer: 1.8.4 (2019-02-11)

When I try to do compose update inside the projects folder or when I try to install a bundle using composer require symfony/swiftmailer-bundle I get the following error:

Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - The requested PHP extension ext-http * is missing from your system.
      Install or enable PHP's http extension.

(It says 'Problem 1', but it is the only problem listed.)

I already looked for the extension in my php.ini file, but I can't find it. Do I need to install an extension manually? If so, where can I find it?

Thanks in advance!